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A089792
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a(n) = n-(exponent of highest power of 3 dividing n!).
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3
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0, 1, 2, 2, 3, 4, 4, 5, 6, 5, 6, 7, 7, 8, 9, 9, 10, 11, 10, 11, 12, 12, 13, 14, 14, 15, 16, 14, 15, 16, 16, 17, 18, 18, 19, 20, 19, 20, 21, 21, 22, 23, 23, 24, 25, 24, 25, 26, 26, 27, 28, 28, 29, 30, 28, 29, 30, 30, 31, 32, 32, 33, 34, 33
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OFFSET
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0,3
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COMMENTS
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The exponent of the highest power of 3 dividing binomial(n,k) is given by a(k)+a(n-k)-a(n).
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LINKS
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FORMULA
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a(n) = log(denominator(n!/3^n))/log(3); a(n) = log_3(A125824(n)). - Paul Barry, Apr 02 2007
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MATHEMATICA
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Table[n-IntegerExponent[n!, 3], {n, 0, 70}] (* Harvey P. Dale, Aug 09 2015 *)
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PROG
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(PARI) vector(70, n, n--; n-valuation(n!, 3)) \\ Michel Marcus, Aug 19 2015
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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